.bottom-btn
  position sticky
  bottom 0
  z-index 1
  display flex
  flex-direction column
  align-items flex-end
  @media ( max-width 768px )
    position fixed
    left 0
    width 100vw
  div
    position absolute
    right 8px
    bottom 8px
  a
    overflow hidden
    display block
    right 0
    width 40px
    height 40px
    color var(--theme-text-light)
    line-height 40px
    text-align center
    font-size 40px
    font-weight 900
    padding 0
    user-select none
    @media ( min-width 769px )
      &:hover
        background-color var(--theme-subcolor)
        color var(--theme-text-hover)
@media ( min-width 769px )
  .i-top:hover
    line-height 30px
.i-color
  display flex
  @media ( min-width 769px )
    &:hover
      line-height 40px
      &::after
        transform rotate(90deg)
  &::after
    margin auto
    content ''
    height 16px
    width 16px
    display inline-block
    border 4px solid var(--theme-bg-light)
    border-radius 50%
    background linear-gradient(45deg, transparent 10px,
      var(--theme-bg-light) 12px, var(--theme-bg-light))
    transition transform .3s, filter .3s
